Death's Only Daughter

A year & a half after leaving, Nico reappears at Camp Half-Blood. Then, a hellhound comes, holding 15 year old Leyla in its mouth. Leyla hasn't been claimed, but when that happens, everyone is shocked, scared, and the only one there to comfort her is Nico. But what happens to their strong friendship when a letter appears under Leyla's pillow that causes her to mysteriously leave?